On Wednesday 2017-12-13 15:29, cagsm wrote:
Date: Wed, 13 Dec 2017 15:29:54 From: cagsm <cumandgets0mem00f@gmail.com> To: "opensuse@opensuse.org" <opensuse@opensuse.org> Subject: [opensuse] Raid, Raid6, what file system for good fault tolerance?
Hi list,
speaking about software raid, not hardware controller based.
I am trying to go for some local OpenSuse machine and adding some storage to it. Was considering Raid6, and now reading about a bit and people left and right scaremongering about the larger the disks these days in the double digit terabyte capacities even, the more likely it is that during a reconstruction of a raid subsequent errors would occur.
I would absolutely like to keep my data consistent, and I am not thinking about double digit terabytes either, would stick to 2TB or 4TB disks, with Raid6 thats at least 4 physical drives.
Now I am wondering if it possible to use a good robust file system that can add some more parity or check blocks or redundancy on top of the hardware disks, to absolutely be able to always read my data.
I can't add multiple machines or like those high availability stuff like clusters and what not I read about DRBD (Distributed Replicated Block Device), or maybe I am just too scared by those technical terms or consider myself to be just a simpleton and wanting to keep it rather simple.
My use case here is also not constant availablity, when a disk needs to be replaced, so be it, but I don't want to lose my data that I can not ever read certain parts of it again or such stuff.
The thing that came to my mind was, if there is some file systems that would add redundancy and robustness onto the mdraid system of the linux kernel?
Anyone with some useful insights? Roughly speaking, I was considering some simple pcie esata interfaced controller card and an external case enclosure with esata port and portmulitplier stuff inside, that can present at least 4 physical disks as JBOD, just a bunch of disks, so that the Linux can seem them all separately.
Speed and rebuild times are not my concern, but data persistence and data integrity. Not even number of physical disks, I could live with even one of those 8 bay device enclosures and cases that are out there on the market.
I have very good experience using RAID 10 for more than 15 years at low cost. Never had data loss.. any journaling filesystem is good. In the past I also used reiserfs, but had the most problem with it. These eSATA enclosures are quite cheap and handy.. 4 disks per enclosure, per eSATA-connector. The HDDs I use are targeted for video or server appliances (24/7 running, very high MTBF), most important, that all(!) hdds have the same geometry, preferably same model and same fw-revision. Keep invoices for RMAs.. Over the years I have got around 30 RMAs.. RAID 10 is very robust, additionaly I always have a hot spare, so up to 3 out of 5 disks could fail under perfect circumstances.. i think cpu load is way lesser than using RAID5 or 6.. an alternative to mdadm software raid could be btrfs raid, but have only experience with RAID 1, and it seems to lack hot spare support. Most sata port multipliers allow also software SMART monitoring. My most recent bought (internal) multipliers also support real hardware raid, but I did not switch yet (maybe on next HDD upgrade, to give it a test). For scalability I also use LVM. Currently I am using EXT4 and XFS filesystems. Never had problems at all on software side. Problematic were cheap SATA-cabling (bad shielding, bad connectors) - very important beside monitoring pending sectors of course is to monitor UDMA_CRC_Error_Count and Load_Cycle_Count. First are an indicator for electromechanical problems and second, power supply - those degrade by time, so I am also monitoring voltages via ACPI. But most important, still: backups. Cheap solution consumer level big HDD. I do daily incremental backups, using two HDDs, which are exchanged regularly (currently weekly) and store the unused one at an fire safe storage place. Best would be a modern LTO-6 or LTO-7 tape drive with loader... but that's unaffordable at the moment.. Just my experience and tips Paul -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org